• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Elac BS U5 Slim 3-way Coaxial Speaker Review

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
34,986
Likes
130,321
Location
Seattle Area
This is a review and detailed measurements of the Elac BS U5 "slim" 3-way coaxial speaker. It is on kind loan from a member. The U5 costs US US $856/pair everywhere so must have price control. I have read that it is designed for the European market with slimmer face and "modern" colors (black and white).

The feel, finish and looks are quite nice:

Elac BS U5 Slim 3-way bookshelf speaker Coaxial Andrew Jones Review.jpg


The coaxial driver above plays mid-range and woofer (or mid-woofer through mid-range and tweeter).

Nothing exciting on the back:
Elac BS U5 Slim 3-way bookshelf speaker Coaxial Andrew Jones Back Panel Binding Posts Review.jpg


Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

Elac BS U5 Slim 3-way bookshelf speaker cea-2034 spinorama frequency response measurements.png


This is an unusual design. On-axis (black solid) is fairly even until about 3 kHz (where the tweeter takes over) but then we have a cycle of ups and downs. Speculating, they are diffraction interfering with the on-axis sound. Early window reflections that are at other angles, hardly show this problem (dashed blue top). There are directivity errors because of this so correction may not be easy with equalization.

We can look at the early window reflections in detail to confirm what I wrote above:

Elac BS U5 Slim 3-way bookshelf speaker cea-2034 spinorama early Reflections frequency respons...png


So no wonder that when we put everything together to predict the in-room response, all seems well:
Elac BS U5 Slim 3-way bookshelf speaker cea-2034 spinorama Predicted In-room Response frequenc...png


Should sound good till we look at the distortion graphs with room effect filtered out:

Elac BS U5 Slim 3-way bookshelf speaker THD distortion percentage frequency response measureme...png


Wow, this is quite a bit of distortion and occurring at crossover points. Is this a design problem with the coaxial driver?

We see the issue quite clearly in the context of overall frequency response:

Elac BS U5 Slim 3-way bookshelf speaker THD distortion frequency response measurements.png


I like to see nothing but blank space past 200 Hz and so yet we have many peaks here. Distortion is so high that I almost think it may be a measurement error but then I look at the review of Elac Adante AS-61 speaker and we have a similar issue:

index.php


That review did not use calibrated SPL levels but still, we clearly see the same rise in distortion at around 270 Hz. And another one before 2 kHz, both of which are near crossover frequencies.

This speaker makes a very good test case of whether distortion is an issue or not in absence of frequency response errors!

Our impedance and phase graph also shows a resonance point:

Elac BS U5 Slim 3-way bookshelf speaker phase and impedance versus frequency measurements.png


We kinda see the first resonance point in the CSD/waterfall as well:

Elac BS U5 Slim 3-way bookshelf speaker CSD waterfall frequency response measurements.png


You can see a trend around 300 Hz which dies down near 6 millisecond mark.

Coaxial driver brings with it good vertical directivity and we see some sign of it here:

Elac BS U5 Slim 3-way bookshelf speaker Horizontal Directivity Audio measurements.png


Elac BS U5 Slim 3-way bookshelf speaker Vertical Directivity Audio measurements.png


Speaker Listening Tests
My first impression of tonality was good. Plenty of warmth due to bass response. Nice ability to play as loud as you want. But yet... the sound is not impressing me. Vocals, both female and male, sounded wrong for example.

I dial in some EQ for the elevated response above 1 kHz and that helps but still not there. I am out of normal tricks with EQ at this point as I usually have a clear guidebook of resonance peaks.

So I applying EQ to the clear distortion peaks. Reduction of level should reduce their levels as we see in the comparison graph of 86 and 96 dB above. I put those in together with my dip for my room mode:

Elac BS U5 Slim 3-way bookshelf speaker Roon Parametric EQ Correction.png


This made a pretty good difference. Sound was more open, with more detail. I kept the Q high so that the impact on the frequency response is low (narrow notches).

At this point speakers became "good." They provide a diffused image which I like (especially since I am listening to a single channel in my reviews).

Conclusions
For a second time we see that the magic of coaxial drivers tends to be more for the eye than the ear. Distortion continues to be quite high and we have wavy output at highest frequencies. Perhaps there is no such thing as a cheap and good coaxial driver.

Or, I could be all wrong and they are fine. :) I tend to be much more sensitive to distortion as party of my training so what bothered me, may not bother others.

Overall, I can't recommend the Elac BS U5. If you apply some equalization as I have, I could be pushed to recommend them for their high power handling and good tonality.

-----------
As always, questions, comments, recommendations, etc. are welcome.

This is the second review of the day. And on weekend no less. I demand overtime pay!!! Please donating what you can so I have something to show for it using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Attachments

  • Elac BS U5 Spinorama.zip
    87.8 KB · Views: 82
Last edited:

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
1,613
Likes
3,719
Location
Canada
index.php


Is the second graph here 96dB and mislabeled? :)

These also seem like pretty bad frequencies to have big spikes in distortion for vocals indeed.
 

ROOSKIE

Addicted to Fun and Learning
Joined
Feb 27, 2020
Messages
864
Likes
1,479
Location
Minneapolis
Very interesting and mirrors my initial listening impressions.(which were positive for the price, but not blown away) I was really interested in how this compared to the 2way dbr-62.
I'd love if Dennis Murphy chimed in here, I know he tried this speaker based on previous comments.
I did think this speaker had excellent bass for such a small driver.
Anyway thanks for another great review!
 

napilopez

Major Contributor
Forum Donor
Joined
Oct 17, 2018
Messages
1,913
Likes
7,230
Location
NYC
Just goes to show how optimized KEF and Genelec's coaxial tech is compared most others.

Interesting, I have a pair of these and the distortion never seemed to bother me. Overall tonality sounded warm/darker to me despite the PIR looking pretty good.

The higher the frequency, the more direct sound you hear relative to room sound, so that's not surprising given the on axis tilt in the upper half of frequencies. This speaker seems like a case of prioritizing off axis over on axis a bit too much.
 
Last edited:

Shazb0t

Senior Member
Joined
May 1, 2018
Messages
464
Likes
775
Location
NJ
The higher the frequency, the more direct sound you hear relative to room sound, so that's not surprising. This speaker seems like a case of prioritizing off axis over on axis a bit too much.
That makes sense. I also toed them in directly to my listening position. The thought behind it at the time being that I would get more of the highs on axis.
 

bigjacko

Addicted to Fun and Learning
Joined
Sep 18, 2019
Messages
528
Likes
253
Thanks for the review, it does show a lot that a company won't tell us. How does eqing the two distortion peaks improve this speaker? Eq them down does reduce the distortion but also reduce the parts that we want. I feel like eq the two distortion peak down is like cutting the organs out due to cancer, fixed one thing but raise another. Anyone with more experience on this?
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
34,986
Likes
130,321
Location
Seattle Area
Thanks for the review, it does show a lot that a company won't tell us. How does eqing the two distortion peaks improve this speaker? Eq them down does reduce the distortion but also reduce the parts that we want.
EQ is certainly not a proper fix. It is a trade off between amplitude correctness and distortion. Since distortion creates harmonics at many frequencies, losing a bit of amplitude response seems to be work.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
34,986
Likes
130,321
Location
Seattle Area
Interesting, I have a pair of these and the distortion never seemed to bother me. Overall tonality sounded warm/darker to me despite the PIR looking pretty good.
It is a very subtle things. If you can try the EQ settings I showed, you can experience it.
 

Gatordaddy

Member
Forum Donor
Joined
Apr 1, 2020
Messages
68
Likes
105
Interesting to see a speaker with few linear response errors but a fair amount of distortion. Also interesting that these appear to measure better than the Adantes. I know the internet hype beast has been pretty polarized on these--and this review doesn't seem to do anything to settle the polarization. I'm still more interested on a measurement of the base models.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
34,986
Likes
130,321
Location
Seattle Area

Shazb0t

Senior Member
Joined
May 1, 2018
Messages
464
Likes
775
Location
NJ
Which base model?
There is a cheaper vinyl wrap model that is shorter and fatter. You reviewed the more expensive painted cabinet model which is tall and "slim". The internal volume of the boxes are reportedly the same with no component changes so I wouldn't expect much if any differences between models.

The "base" model would routinely go on sale for ~$350/pair.
 

ROOSKIE

Addicted to Fun and Learning
Joined
Feb 27, 2020
Messages
864
Likes
1,479
Location
Minneapolis
Which base model?
Howdy this speaker is the slim version of the UB5, and is called the BS 5. The regular UB5 is $579. It is however covered in the very cheap type of vinyl. Still same sound for less $$
The BS 5, does often also hit sale price lowes in the $600 range.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
34,986
Likes
130,321
Location
Seattle Area
There is a cheaper vinyl wrap model that is shorter and fatter. You reviewed the more expensive painted cabinet model which is tall and "slim". The internal volume of the boxes are reportedly the same with no component changes so I wouldn't expect much if any differences between models.

The "base" model would routinely go on sale for ~$350/pair.
Ah, I was told about that. I thought you were talking about a different speaker altogether.

Is it worth measuring though? Likely would be the same as this one.
 

Shazb0t

Senior Member
Joined
May 1, 2018
Messages
464
Likes
775
Location
NJ
Ah, I was told about that. I thought you were talking about a different speaker altogether.

Is it worth measuring though? Likely would be the same as this one.
@Gatordaddy For what it's worth, I agree with Amir that if he did measure the vinyl wrap cabinet model he likely wouldn't see any differences from these measurements apart from speaker to speaker variance.
 
Top Bottom